1. Technical Field
The present invention relates generally to a system for regulating the flow of a pressurized gas from a tank and, in particular, to an improved fill valve and to an improved constant flow regulator.
2. Description of the Prior Art
Systems for providing a pressurized gas to a use location, such as supplemental oxygen delivery to a medical patient, are known. The known oxygen delivery systems typically include a gas pressurizable tank which stores the oxygen under relatively high pressure. A regulator is operably connected to the tank for controlling the rate of flow of the pressurized gas from the tank to the use location.
When such delivery system is used for providing oxygen for "at home" use, a physician or medical technician prescribes a flow rate at which the oxygen is to be supplied to the patient as a function of the patient's need. The patient sets the known regulator to the prescribed flow rate, but the actual flow rate may vary as a function of pressure within the tank. As the pressure in the tank decreases with use, the actual flow rate of oxygen from the tank can increase or decrease from the initial prescribed rate which was set by the patient. If the patient does not frequently monitor and adjust the actual flow rate, an insufficient oxygen supply could be delivered or excess oxygen could be delivered and wasted. These are both undesirable situations.
Fill valves are also operably connected with the gas pressure tank. The known fill valves typically are opened and closed manually during filling and evacuation. Evacuation of the tank is required for medical oxygen to assure that no contaminants are present in the tank prior to re-filling the tank with purified oxygen.